C++ Program to Sort the given matrix

Given a n x n matrix. The problem is to sort the given matrix in strict order. Here strict order means that matrix is sorted in a way such that all elements in a row are sorted in increasing order and for row ‘i’, where 1 <= i <= n-1, first element of row 'i' is greater than or equal to the last element of row 'i-1'.
Examples: 

Input : mat[][] = { {5, 4, 7},
                    {1, 3, 8},
                    {2, 9, 6} }
Output : 1 2 3
         4 5 6
         7 8 9

Approach: Create a temp[] array of size n^2. Starting with the first row one by one copy the elements of the given matrix into temp[]. Sort temp[]. Now one by one copy the elements of temp[] back to the given matrix.

C++

// C++ implementation to sort the given matrix
#include <bits/stdc++.h>
using namespace std;

#define SIZE 10

// function to sort the given matrix
void sortMat(int mat[SIZE][SIZE], int n)
{
    // temporary matrix of size n^2
    int temp[n * n];
    int k = 0;

    // copy the elements of matrix one by one
    // into temp[]
    for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++)
            temp[k++] = mat[i][j];

    // sort temp[]
    sort(temp, temp + k);

    // copy the elements of temp[] one by one
    // in mat[][]
    k = 0;
    for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++)
            mat[i][j] = temp[k++];
}

// function to print the given matrix
void printMat(int mat[SIZE][SIZE], int n)
{
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++)
            cout << mat[i][j] << " ";
        cout << endl;
    }
}

// Driver program to test above
int main()
{
    int mat[SIZE][SIZE] = { { 5, 4, 7 },
                            { 1, 3, 8 },
                            { 2, 9, 6 } };
    int n = 3;

    cout << "Original Matrix:
";
    printMat(mat, n);

    sortMat(mat, n);

    cout << "
Matrix After Sorting:
";
    printMat(mat, n);

    return 0;
}

Output:  

Original Matrix:
5 4 7
1 3 8
2 9 6

Matrix After Sorting:
1 2 3
4 5 6
7 8 9

Time Complexity: O(n²log₂n). 
Auxiliary Space: O(n²).

Please refer complete article on Sort the given matrix for more details!